86 



EDENTATA. 



Genus MEGATHERIUM, Cuvier\ 



In the type species the dentition is -, but in the nominal M. ger- 

 vaisi, H. Gervais and Ameghino^, there are said to be only three 

 lower teeth. The teeth consist of square prisms wearing into 

 transverse ridges through the presence of two vertical plates of hard 

 dentine ; they are similar in structure, and have no diastema ; the 

 hinder part of the mandibular ramus forms a deep descending plate. 

 The external trochlear ridge of the astragalus for the tibia is very 

 prominent, and is raised much above the internal tibial protuber- 

 ance ; there is a deep navicular cup in the astragalus. The second, 

 third, and fourth digits of the manus and the third in the pes have 

 claws, the third being the longest. The second and third phalan- 

 geals of the third digit are anchylosed in both the manus and the 

 pes. There is no entepicondjdar foramen in the humerus. 



Megatherium americanum, Cuvier^ 



Syn. Megatheriuon cuvieri, Desmarest^. 

 Megatheiniini australe, Oken'. 

 Bradypus giganteus, Pander and D'Alton ^. 



This is the type species, and larger than Rhinoceros unicornis. 



Hah. South America (Argentine Republic and Uruguay). 

 * Cast of the skeleton. This specimen is made up partly from 

 casts of bones in the Museum, which were obtained in 

 1837 from the Pleistocene of Luj an, Buenos Ayres, Argen- 

 tine Republic, and partly from those of others preserved 

 in the Museum of the Eoyal College of Surgeons (No. 

 34:41), which were obtained by Sir Woodbine Parish from 

 the bed of the Rio Salada, one of the tributaries of the Rio 

 Plata, south of the city of Buenos Ayres. The restored 

 skeleton is figured in pis. i. and xxvii. of Owen's ' Memoir 

 on the Megatherium' Purchased. 



19953. The sknll, with the cerotahyals attached; from Lujan. 



(Fig.) This specimen, from which the cast of the skull in the 

 restored skeleton is taken, is figured by Owen, op. cit. 

 pis. xii.-xvi., the figure of the mandible being copied in 

 woodcut, fig. 18. Purchased, 1846. 



1 Table Elem. de I'lTist. Nat. p. I-IG (1708). 



2 'Mainiiiiferes Fossiles de rATneriquo Mcridionale,' p. 130 (1880). 



3 in Shaw's ' General Zoology,' vol. i. p. 165 (1800). 

 '» Maminalogie, p. 3(55 (1822). 



^ Tn JIoll's ' llandbuoh der Petrefaotenkunde,' p. 27 (1829). 

 « Kiesenfaulthier, &c. pi. i. (Bonn, 1821). 



